scholarly journals Thermal Fatigue Behavior of Air-Plasma Sprayed Thermal Barrier Coating with Bond Coat Species in Cyclic Thermal Exposure

Materials ◽  
2013 ◽  
Vol 6 (8) ◽  
pp. 3387-3403 ◽  
Author(s):  
Zhe Lu ◽  
Sang-Won Myoung ◽  
Yeon-Gil Jung ◽  
Govindasamy Balakrishnan ◽  
Jeongseung Lee ◽  
...  
2009 ◽  
Vol 75 ◽  
pp. 31-35 ◽  
Author(s):  
Chang Che ◽  
G.Q. Wu ◽  
Hong Yu Qi ◽  
Z. Huang ◽  
Xiao Guang Yang

The aluminum depletion of NiCrAlY bond coat in an air-plasma-sprayed thermal barrier coating (TBC) has been studied by experimental and simulative approaches. Upon thermal exposure, Al depletion regions were observed. The depletion of aluminum is resulting from Al diffusion towards the surface of bond coat and into substrate. A mathematical model of Al depletion was presented. The model is able to explain the observed results in a qualitative way and has been shown that Al depletes within the bond coat by diffusion.


2019 ◽  
Vol 360 ◽  
pp. 140-152 ◽  
Author(s):  
Chunshan Zhao ◽  
Lirong Luo ◽  
Jie Lu ◽  
Xiaofeng Zhao ◽  
Xin Wang ◽  
...  

Author(s):  
J. Allen Haynes ◽  
Mattison K. Ferber ◽  
Wallace D. Porter ◽  
E. Douglas Rigney

Thermogravimetric methods for evaluating bond coat oxidation in plasma-sprayed thermal barrier coating (TBC) systems were assessed by high-temperature testing of TBC systems with air plasma-sprayed (APS) Ni-22Cr-10Al-1Y bond coatings and yttria-stabilized zirconia top coatings. High-mass thermogravimetric analysis (at 1150°C) was used to measure bond coat oxidation kinetics. Furnace cycling was used to evaluate APS TBC durability. This paper describes the experimental methods and relative oxidation kinetics of the various specimen types. Characterization of the APS TBCs and their reaction products are discussed.


Author(s):  
X. J. Wu ◽  
P. C. Patnaik ◽  
M. Liao ◽  
W. R. Chen

Thermal barrier coatings (TBC), which consist of yttria-partially-stabilized zirconia top coat and metallic bond coat deposited onto superalloy substrate, are favorably used as protective coatings of the hot section parts in advanced gas turbine engines to withstand increased inlet temperatures and thus improve engine performance. However, understanding and modeling the damage evolution in TBC under service exposed conditions still remain to be a challenge. This is due to the failure by the coupled effects of the external load-environment, the thermal expansion mismatch between the bond coat and TBC, microstructure of the coating, and degradation of the bond coat. In this study, the damage state in an air-plasma-sprayed APS) thermal barrier coating system was assessed using metallurgical and statistical methods. The damage evolution in the TBC can thus be described with a high degree of confidence. A mechanistic model, representing the micro-cracking mechanism, is presented and its prediction is also assessed on a statistical basis.


Author(s):  
W. R. Chen ◽  
X. Wu ◽  
B. R. Marple ◽  
X. Huang ◽  
P. C. Patnaik

The degradation of a thermal barrier coating (TBC) system is dominated by the formation and growth of a thermally grown oxide (TGO) layer between the ceramic topcoat and metallic bond coat, leading to a separation near the ceramic/bond coat interface during service. Crack propagation in a thermally sprayed TBC normally proceeds via the opening and growth of pre-existing discontinuities in the ceramic layer near the ceramic/bond coat interface region assisted by cracking associated with the evolution of the TGO. The combined effect of these degradation processes results in premature TBC failure. In the present study, TGO growth and cracking behaviours were investigated under cyclic oxidation conditions with different cycle frequencies. The results showed a likely relationship between the maximum crack length and TGO thickness, suggesting that the establishment of an empirical formula may be possible to serve as the basis for a TBC life prediction model.


Sign in / Sign up

Export Citation Format

Share Document